Typically, uniformly etching substrates using plasma (e.g., ionized gases) generated by microwave or radio frequency power can be difficult to accomplish.
Conventional hardware and processing techniques may result in a non-uniform distribution of ions or plasma density across the substrate. The plasma density non-uniformity may result in non-uniform etching or removal of portions of the substrate. Traditional plasma sources may generate non-uniform plasma density across the substrate based on the location of the plasma source relative to the substrate. Generally, plasma sources are located opposite or parallel to the substrate. Unfortunately, plasma sources may not uniformly emit power across their surface to generate a uniform plasma density across the substrate. This may be due to the inability to emit power uniformly at the edge of the plasma source. Increasing the size of the plasma source to improve plasma density uniformity across the substrate may not be practical or possible. Thus, any means that can improve the plasma density near the edge of the substrate would be desirable.